Plastic bag



Oct. 21, 1969 w. 0. G6T2 3,473,589

PLASTIC BAG Filed Dec. 9. 1966 2 24a /2 m /4 22 26 v I "I!IIIIIIIIIIIIIIIIIl/n 'IIIIIIIIIIIIII/IIIIIIIII' -,II,

22 Z4 Z0 32 /6 (30 A8 F1 g: 2 22 26 m 30 /4 ,flmfll III II II II II IIII i ll I II n INVENTOR.

WALTER 0. G6T2 BY ATTORNEYS nite States Patent m 3,473,589 PLASTIC BAGWalter O. Gtitz, Nenstadt, Germany, assignor to Minigrip, Inc.,Orangeburg, N.Y., a corporation of New York Filed Dec. 9, 1966, Ser. No.607,346 Claims priority, applieEatioiggrmany, Dec. 11, 1965, 3 Int. Cl.A45c 13/10; B65d 1/00 US. Cl. 150-3 8 Claims ABSTRACT OF THE DISCLOSUREA closure structure for a container and a method of making the structurewith the structure having a first thin inner layer of flexible plasticmaterial with a first fastener element extending therealong being of onepiece with the layer and a second thin inner layer of flexible plasticmaterial facing the first layer and having a uniform second fastenerelement extending therealong formed of a resilient material and being ofone piece with the second inner layer and shaped to be releasablyinterlocked with the first fastener, a first outer layer positioned overthe outer surface of the first inner layer and laminated thereto, asecond outer layer positioned over the outer surface of the second innerlayer and laminated thereto with each of the inner layers providing aresilient support for the fastener elements and the outer layersproviding a backin for the support.

BACKGROUND OF THE INVENTION The invention relates to a material havingflexible pressure interlocking releasable fasteners or interlockingelements extending therealong for forming bags or similar articles forcontaining items such as perishable goods.

Heretofore bags with pressure fastenable releasable interlockingelements for closures have been formed in various ways with onearrangement forming the fastener strips and attaching them to the topedges of the bags. Additional developments have embodied forming thefastener elements to be of one piece with the material of the bag. Aprimary consideration in the formation of such material with a fastenerelement is the satisfactory operation of the fastener elements. This isof paramount importance inasmuch as fastener elements which do notinterlock properly or which can easily become accidentally opened are oflittle use and are particularly disadvantageous for containers formaterials such as food stuffs where air and dirt can contaminate thecontents. In order to have a satisfactory fastener element, theinterlocking portions of the element must be related to each other andto the backing material in such a way that they can readily be closed byapplying pressure to the outer surfaces of the material and can readilybe opened by pulling the elements apart such as by separating connectedopening flanges. There are many considerations and factors which are notobvious from merely viewing a fastener structure which have a bearing onits effieiency and usefulness. The fastener structure must be such thata container, and particularly the supporting walls for the fastenerelements can take loads such as are encountered when the bags arestacked or can take rolling and twisting such as occurs with handlingwithout inadvertently opening. The fastener structure must be so relatedto the supporting wall that it can be intentionally drawn open whendesired without tearing the parts and without making them incapable ofreuse.

To make an improved flexible closure it is necessary to make theinterlocking rib and groove elements stronger to resist inadvertentopening and be more airtight. This of course makes the elements harderto separate inten- 3,473,589 Patented Oct. 21, 1969 tionally, and alsoincreases the stress between the supporting elements and the fiber wallson which they are carried. Because material having elastic propertiesmust be used for the fastener elements the supporting walls normallyhave the disadvantages of the elasticity of the material. In the presentinvention adequate strength is obtained for the walls supporting theelements without necessitating increasing the wall thickness an undueamount; that is by using a backing lamination for the wall, particularlyat the place of support, having the support properties desired.

It is an object of the present invention to provide an improved combinedfastener and material therefor and method of making which makes possiblethe formation of an improved reopenable container.

More particularly an object of the invention is to provide an improvedfastener and supporting material therefor that lends a superior supportrelationship between the interlocking element and the supporting wall ofmaterial which has improved faculties for opening the fastener, keepingthe fastener closed, and permitting reopening and reclosing.

A feature of the invention is the provision of an interlocking elementwhich is made of one piece with an inner layer of a wall of material andwherein an outer layer is laid over the inner layer and laminatedthereto so that support is afforded for the fastener element directly bythe inner layer and reinforcing by the outer layer and a carryingplatform or support is provided for the inner layer by the outer layerso as to afford an overall coaction between the fastener and the twolayers and the line of lamination therebetween.

Other objects, advantages and features will become more apparent withthe teaching of the principles of the invention in connection with thedisclosure of the preferred embodiments thereof in the specification,claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a sectional view takenthrough a layer of material constructed in accordance with theprinciples of the present invention;

FIGURE 2 is a sectional view taken through the top of a container formedof the material of FIGURE 1; and

FIGURE 3 is a sectional view through another form of construction of theinvention.

DESCRIPTION OF THE PREFERRED As shown in FIGURE 1, a first thin innerlayer 10 of flexible plastic material is provided having a firstfastener element 12 extending therealong. The fastener elements 12 and14 are complementary shaped for pressure interlocking and for beingreleased when drawn apart. They are shown with the interlocking element12 being a female element having projecting sides and the element 14being a male element to be gripped by the element 12 when in theinterlocked position as illustrated in FIGURE 2. The interlockingelements may take various forms and the element 14 may be arrowheadshaped with the element 12 having overhanging sides to grip behind thehead of the arrow. In the type of interlocking fastener shown, it isessential that the lips or sides of the element 12 be sufficentlyflexible to bend when the element 14 is pressed into the groove formedbetween the sides and the immediate base of the elements is preferablyof the same material as the elements, yet the overall support for theelements must not tear or permanently stretch when the elements areseparated such as when a bag is intentionally opened. The support forthe fastener elements therefore constitutes an important part of thefunction of the elements making them capable of remaining interlockedduring normal usage in handling, permitting them to be rigidlyinterlocked when pressed together, and permitting them to be openedwhen' necessary.

On the opposite side of the inner layer is an outer layer 16 which ispositioned over the outer surface of the inner layer 10 and laminatedthereto. The inner layer 10 may be a flexible plastic material such aspolyethylene and the outer layer forms another layer of material whichaffords mounting or a carrying support for the inner layer 10 providinga superior functional relationship particularly at the location wherethe fastener elements 12 and 14 are carried. In some instances, theouter layer 16 may be formed of a material such as polypropylene or maybe formed of a metallic foil. In addition to providing a support for thefastener elements, the outer layer combined with the inner layer forms acomposite wall which is substantially impervious to the penetration ofmoisture. In the formation of a plastic layer such as the inner layer 10small minute holes often occur which extend through the material. Bylaminating the second layer to the first, these holes will be closed anda superior wall material will be provided.

As to the fastener elements 12 and 14, the flanges of the elements ifmade long or thin will tend to tear if the elements provide too strong alock. By providing the present combination of elements, the outer layer16 provides extra strength to the inner layer location of the flanges sothat a strong lock can be used for the fastener element 12 and asuperior strength and a tighter fastener is achieved than if a singlelayer were used. Further the outer material can be a stronger material(better suited for strength or support than the inner layer) such aswhere the inner layer is polyethylene and the outer layer ispolypropylene. This makes it unnecessary to use an unnecessarily thickmaterial to obtain the necessary strength.

FIGURE 1 may be considered as presenting a single sheet or wall or asplural walls. If separate sheets 30 and 32 are used to make a bag orcontainer, these sheets are welded or seamed together at their base andedges. If desired, the wall or sheet shown can be made as a single unitsuch as by being extruded from a die in one pass or the single sheet canbe extruded in tubular form with the tube being slit along its length toform the sheet.

The sheet or wall 32 has an upper flange portion 24a on one side with abody portion on the other side. Similarly the wall 30 has a flangeportion 22a on one side of the fastener element 14 and the body portionon the other side. The flange portions 22a and 24a have lines ofweakened tear resistance 26 and 28 respectively. This is illustrated inFIGURE 2 with the areas 22 and 24 above the tear lines 26 and 28 beingjoined together to form a removable tear strip.

For the purpose of the tear strip, the outer layers 18 and 20 can bearranged to extend only to the tear strip thus accommodating more easilyseparation of the tear strip and actually providing a stronger backingfor the material below the tear strip to facilitate better tearing.Further, the completed bag as it appears after the tear srip (formed ofthe areas 22 and 24) is removed, has the outer layers 18 and 20extending to its top edge with the upper edges of the outer layers shownat 18 and 20 to provide the grippable flanges to separate the fastenerelements 12 and 14.

In the arrangement of FIGURE 3, the tear line of weakened resistance hasbeen omitted and the edges at 34 are thinned so that the entire edgescan be removed.

The upper edges as formed by the areas 22 and 24, or formed by theportions 34 can be joined by being passed through a heated Pressingmeans, or, if desired, if the entire unit is extruded longitudinally asa tube they can be formed in one piece initially.

While the resultant bag which is formed as shown in FIGURES 2 and 3 isair and moisture tight if the outer layer 16 extends over the entirearea, it is possible that the top, at the location of the tear lines 26and 28, and/ or any other areas that may require reinforcing can becoated with a sealing lacquer so that the required impermeability isabsolutely assured.

When the separate sheets or walls 30 and 32 (or the single wall if thematerial is manufactured in one piece! are formed, after the inner layerhas been extruded, with the fastener elements 12 and 14 being of onepiece therewith and extruded concurrently therewith in accordance withthe present method, the outer layer 16 is then POSI- tioned over theouter surface of the inner layer 10. it IS then laminated to the innerlayer by known methods such as by including a thin layer of cement orthermoplastic adhesive between the layers. Or, if desired, the outerlayer can be positioned and heat applied in a relative manner so as tomerely join the two layers to accomplish the lamination. This actuallycauses a lamination layer at the juncture between the inner and outerlayers 10 and 16 and this juncture functions further to provide superiorsupport for the fastener elements 12 and 14. As forces on the exteriorof the bag or on the bag walls tend to bend the fastener elements, theywill yield limitedly with the resilient support afforded by theresilient plastic inner layer 10. This support is backed by the line ofjuncture or lamination between the inner layer 10 and 16, and the outerlayer provide a support of strength and protection for the inner layerat the place where it supports the fastener elements 12 and 14. Byproviding a laminated outer layer. preferably less elastic or strongerthan the inner layers. the fastener elements can be integral or of onepiece with the bag wall, can be made of material of good elasticproperties as is necessary for the elements, and can be very strong withthe bag wall havingadequate strength without excessive thickness. Theforcefi/hich occur at the fastener elements as they are separated tendto be transmitted or absorbed by the laminated material and particularlythe strong outer layer. Also as stresses occur and tend to stretch theinner layer of material, they will not create a breach or tear in theouter surface of the material. This makes possible a substantiallystronger fastener structure than has heretofore been available.

Thus it will be seen that I have provided an improved fastener structurematerial which meets the objectives and advantages above set forth. Thematerial provides a light weight strong structure. If a single layer ofmaterial were used, of suflicient weight to stand the stresses of astrong fastener the wall and the integral fastener elements can beformed in a single extrusion process but this creates uneven cooling andstresses in the inner layer. However, with the structure of the presentinvention the outer layer is not affected by unequal cooling and unevenstresses are not introduced due to stretching, during extruding,providing a material which has a strength superior to other material ofthe same thickness which has been formed in a single layer.

The drawings and specification present a detailed disclosure of thepreferred embodiments of the invention, and it is to be understood thatthe invention is not limited to the specific forms disclosed, but coversall modifications. changes and alternative constructions and methodsfalling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a closure structure for a container or the like, in combination,

a first thin inner layer of flexible plastic material having a uniformfirst fastener element extending therealong formed of a resilientmaterial and being of one piece with said layer,

a second thin inner layer of flexible plastic material facing said firstlayer and having a uniform second fastener element extending therealongformed of a resilient material and being of one piece with said secondlayer and shaped to be releasably interlocked with the first fastenerelement,

a first outer layer positioned over the outer surface of the first innerlayer and laminated thereto,

said first inner and outer layers providing a first substantiallymonolithic wall so that said first inner layer provides a support forthe first fastener element and the first outer layer provides a backingfor the support with said layers coacting and allowing a stronger lockwith a thin film,

and a second outer layer positioned over the outer surface of the secondinner layer and laminated thereto, said second inner and outer layersproviding a second substantially monolithic wall so that said secondinner layer provides a support for the second fastener element and thesecond outer layer provides a backing for the support allowing astronger lock with a thin film, said outer layers laminated to the innerlayer opposite fastener elements so as to reinforce the inner layers inthe area of said fastener elements.

2. In a closure structure for a container or the like in accordance withclaim 1 wherein the combination includes the outer layers having a yieldstrength greater than said inner layers.

3. In a closure structure for a container or the like in accordance withclaim 1, wherein the combination includes said inner layers being ofpolyethylene and said outer layers being polypropylene.

4. In a closure structure for a container or the like in accordance withclaim 1 wherein the combination includes the inner layers being formedof a resilient plastic and said outer layers being formed of a metallicfoil.

5. In a closure structure for a container or the like in accordance withclaim 1 wherein the combination includes,

first and second Walls being joined to each other below the fastenerelements to form a container and extending above said first and secondelements providing separating flanges which may be drawn away from eachother for detaching said first and second elements and separating thewalls to open the container.

6. In a closure structure for a container or the like in accordance withclaim 5 wherein said flanges are joined at an upper location spacedabove said elements and have a line of weakened tear resistance formedbetween said joined location and said fastener elements.

7. In a closure structure for a container or the like in accordance withclaim 6 wherein said outer layers extend upwardly to terminate adjacentsaid line of weakened resistance and the area above said line containsonly the inner layer for accommodating tearing of the line of weakenedresistance and removal of the material of the inner layer above saidline.

8. In a closure structure for a container or the like,

in combination,

a thin inner layer of flexible plastic material having a uniformstraight fastener element extending therealong formed of a resilientmaterial and being of one piece with the layer,

said fastener element spaced inwardly from one edge of the plasticmaterial forming a flange portion and being spaced inwardly from theopposite edge forming a body portion,

and a thin outer layer of material positioned over the surface of theinner layer opposite the fastener element and laminated thereto,

said layers providing a substantially monolithic wall for combining withanother Wall to form a container with said other wall having anotherfastener element shaped to releasably interlock with the first fastenerelement,

said outer layer laminated to the inner layer directly opposite saidfastener element so as to reinforce the inner layer at the area of thefastener element.

References Cited UNITED STATES PATENTS 2,519,290 8/1950 Saltz -32,780,261 2/1957 Svec et a1 150-3 2,861,022 11/1958 Lundsager 229-35 X2,916,197 12/1959 Detrie et al 150-3 X 3,132,742 5/1964 Shapiro et al.229-54 X 3,122,297 2/1964 Sachs 150-1 X 3,136,468 6/1964 Keller 229-353,198,228 8/1965 Naito 150-3 DONALD F. NORTON, Primary Examiner U.S. Cl.X.R. 150-1; 22-9-55

